13 egg white

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    13. Egg WhiteRenate Landig

    German Team

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    Task

    White light appears red when it is

    transmitted through a slice of boiled egg

    white. Investigate and explain this

    phenomenon. Find other similar examples.

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    Overview

    Experiments

    Structure of Egg White

    Theory

    Rayleigh Scattering

    Similar Examples

    Modified Rayleigh Scattering

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    Experimental Setup

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    Basic Experiment

    Unpolarized white light

    0.15 mm solid egg white

    the screen behind the slice:

    spectrum with sample

    without

    prism

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    Spectrometer

    280nm: absorption maximum

    Boiled egg (d=0.1mm)

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    Structure of Egg White

    mixture of proteins in water

    protein: 20 different amino acids

    unfolding through heat input

    reactions between proteins

    unstructured network (random coil) density fluctuations scattering

    Denaturated egg white:

    Liquid egg white:

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    Scattering

    Wave excites particles oscillation

    Hertzs dipole

    Scattering fields

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    Derivation of E-field

    P

    Er

    _O

    2

    2

    dt pdtdIdtdBE 0

    2EE

    rE

    1

    ckc ==

    2

    (1) tiepp

    0=

    (2)

    sinE

    (3)

    (4)

    sin

    40

    2

    0

    r

    kEE=

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    Unpolarized Light

    ||

    E

    ||E

    ||,0E

    ,0E

    .

    cos

    4 0

    2

    ||,0||r

    kEE = 2

    0

    2

    ,0 sin4

    r

    kEE =

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    Rayleigh Scattering

    2

    ||

    22EEE +=

    0

    22

    0

    2

    4

    2

    )cos1(

    4 Ir

    k

    I

    +

    =

    4

    42 1d

    = krIP

    2

    EI

    The radiant power of one particle:

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    Extinction

    xII

    = e0

    4

    1ln

    0 == x

    I

    I

    Lambert-Beers Law:

    Extinction:

    nPn

    I I

    dI, dx

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    Comparison with Experiment

    800nm 350nm

    expected

    measured

    1

    1.2

    0.8

    1.8

    1.6

    2

    1.4

    extinc

    tion

    [1]

    -4254m10

    2 5431

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    With Interference

    2scatincsin2

    cos

    bkkrkr

    rb

    ==

    =

    r

    r

    r

    r

    r

    P

    O

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    Modified Rayleigh-Scattering

    2

    2i

    sin

    )sinsin(1de

    1)(

    2

    2

    a

    ka

    kbA

    AaR

    a

    a-

    ==

    2

    Rlgh )(RII

    =

    ( )=

    cos1

    4 0

    2

    0

    ||

    Rr

    VkEEE

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    Dependence on

    ( )

    +

    =

    ka

    P

    rIP

    dsin

    sinsin

    2

    cos11

    d

    2

    2

    2

    2

    2

    2

    (k) is only slightly dependant onk

    2

    1

    P

    )(k

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    Extinction- -plot2

    1.8

    extinctio

    n

    [1]

    1.4

    1.6

    1

    1.2

    0.8

    -2122m10

    2.5 43 54.53.5

    1.8

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    Similar Examples (1)

    Sunset / Lunar eclipse

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    Similar Examples (2)

    Milk in water

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    Similar Examples (3)

    Polyethylene: e. g. white plastic bag

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    Similar Examples (4)

    Ouzo in water

    without

    liquid

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    13. Egg WhiteRenate Landig

    German Team